1. Field of the Invention
The present invention relates to a machine for installing drip irrigation conduit, and more particularly to such a machine for automatically installing pipe prepared conduit consisting of hose to be buried in the earth and a plurality of risers spacing along the hose and extended in an erect disposition upwardly from the hose, the machine being particularly adapted for use in installing large-scale irrigation systems and for installing the conduit beneath and adjacent to existing plants in an orchard or the like.
2. Description of the Prior Art
Drip irrigation, in which water is applied to the earth in a controlled amount adjacent to each plant, provides the maximum utilization of water since little water is lost due to evaporation or due to application where water will run off or otherwise not reach the plant roots. A particularly effective method of drip irrigation, which is effective with new or existing orchards, vineyards and the like, is to bury a hose along a row of plants to be irrigated and beneath the earth surface where the hose is unlikely to be damaged by implements or animals and to provide the hose with risers extended upwardly therefrom to points individually adjacent to the plants and above the earth surface. It is known to facilitate the installation of such conduit by the use of preprepared conduit in which the risers are mounted on the hose for pivotal movement in a plane normal thereto before the conduit is installed.
It is possible to avoid the use of risers extended above the earth surface by utilizing buried emitters spaced along a length of buried pipe or hose. However, such buried emitters are likely to be blocked by the growth of roots from the plants being irrigated and this blockage is difficult to detect or to correct.
It is known to install drip irrigation conduit by laying hose or somewhat flexible pipe in a predetermined route along the earth surface and then, in a subsequent operation, moving an implement along the route to form a furrow of the usual trough-like configuration along the route while the hose or pipe is carried upwardly over the implement and placed in the furrow, the furrow subsequently being backfilled. This method of installing conduit is also usable when the conduit is preprepared with risers, however, it is necessary with such preprepared conduit manually to manipulate the conduit to ensure that the hose or pipe is at the proper depth and that the risers remain erect during backfilling. It is also known to bury such hose or pipe by passing it into a moving cavity being continuously formed and refilled by a blade moving beneath the earth surface, the hose or pipe being passed from above the earth surface through an opening in a shank of the blade into such cavity. Conduit preprepared with risers cannot be used with the latter method since the risers cannot pass through the opening and, in any event, the risers would not necessarily be disposed in an erect disposition when the cavity closes.
In existing methods of installing drip irrigation conduit, a ripper blade is used which extends downwardly to a depth approximately twice the depth of the furrow bottom or cavity formed by the blade. As a result the roots of existing plants, including the larger and deeper roots, are damaged to a depth below that required for actually laying the conduit. Further, existing implements for installing irrigation conduit are disadvantageous for laying drip irrigation conduit in the most desirable position which is a position close to the trunks of existing trees or vines. This is because existing implements for this purpose not only cause extensive root damage, but because they engage and break off and otherwise damage lower branches. Such existing implements are also illsuited to the use of a reel wound with preprepared conduit having a flexible hose. Such use of a reel reduces the required number of operations in installing drip irrigation conduit, but is particularly disadvantageous with existing implements because the reel is disposed above the implement and would damage the higher branches of existing plants as well as their lower branches.
Underground laterals for sprinkler irrigation systems having risers extending from the laterals to above ground spray heads are installed with a device resembling a pair of ripper blades disposed in adjacent spaced relation to define a slot. Polyvinylchloride, "PVC", pipe preprepared with risers is laid along the route as described above and fed into the slot for burial in a furrow formed by the blades as they move through the earth. Fingers fixedly mounted on the blades extend transversely into the slot and maneuver each riser to that it arrives in the furrow in an erect disposition. Such a device, although causing the root damage described in the previous paragraph, is effective with PVC material which is relatively strong and has the risers adhesively connected to the pipe in a manner giving strength equal to that of the material itself. PVC also possesses "memory" so that the risers tend to assume an erect position if preprepared in such a position. However, it is undesirable to use PVC material with drip irrigation systems because of its rigidity and expense compared to polyethylene material which is sufficiently strong to withstand the lower pressures used in drip irrigation. The device just described for use with PVC material is not effective with polyethylene because the weaker material itself cannot withstand the stretching as the hose is drawn over the fingers and the impact of the fingers on the hose and risers. In any event, such stretching pulls apart the connections between polyethylene hoses and risers which are friction tight and thus easily and economically formed. Even if preprepared, drip irrigation conduit of polyethylene material cannot withstand the stresses inherent in such a device, this material lacks "memory" and the risers would not assume the required erect disposition.
The prior art is replete with agricultural implements for generating a furrow in the earth surface, and it is known to precede a conventional moldboard plow with a planar, discoidal coulter having a substantially horizontal axis extended transversely of the direction of movement of the implement in generating a furrow. However, insofar as known to the applicant, it is not known to use such a coulter and plow with a second such coulter having its axis inclined to the horizontal so that the two coulters and plow generate a furrow having a substantially upright wall and an opposite wall extended in upwardly diverging relation to the upright wall at an acute angle to the vertical.
Despite the deficiencies of existing implements for installing drip irrigation conduit, which deficiencies include multiplicity of operations, excessive manual manipulations, and damage to plants, the advantages of drip irrigation at a time when the need to conserve water is imperative are such that thousands of acres are being provided with such conduit. It is apparent, therefore, that a machine which installs preprepared drip irrigation conduit having erect risers in one operation and which substantially avoids damage to existing plants is highly advantageous, provides substantial reduction in cost, and allows the water savings of drip irrigation systems to be further extended.